Method for resizing pattern to be written by lithography technique, and charged particle beam writing method

ABSTRACT

A method for resizing a pattern to be written by using lithography technique includes calculating a first dimension correction amount of a pattern for correcting a dimension error caused by a loading effect, for each small region made by virtually dividing a writing region of a target workpiece into meshes of a predetermined size, based on an area density of the each small region, calculating a second dimension correction amount in accordance with a line width dimension of the pattern to be written in the each small region, correcting the first dimension correction amount by using the second dimension correction amount, and resizing the line width dimension of the pattern by using a corrected first dimension correction amount, and outputting a result of the resizing.

CROSS-RELATION TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2006-249141 filed on Sep. 14,2006 in Japan, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for resizing a pattern to bewritten by lithography technique, and a charged particle beam writingmethod. More particularly, for example, the present invention relates toa method of previously resizing a pattern by using a dimension changeamount of the pattern which is produced by a loading effect whenperforming a pattern forming after writing the pattern using electronbeams, and to a writing method and apparatus for writing a pattern on atarget workpiece based on resized pattern data using electron beams.

2. Description of the Related Art

Microlithography technology which forwards miniaturization ofsemiconductor devices is extremely important, because only this processperforms forming a pattern in semiconductor manufacturing processes. Inrecent years, with an increase in high integration and large capacity oflarge-scale integrated circuits (LSI), a circuit line width required forsemiconductor elements is becoming narrower and narrower. In order toform a desired circuit pattern on these semiconductor devices, a masterpattern (also called a mask or a reticle) with high precision isrequired. Then, since the electron beam (EB) technology for writing or“drawing” a pattern has excellent resolution intrinsically, it is usedfor manufacturing such high precision master patterns.

FIG. 14 shows a schematic diagram describing operations of aconventional variable-shaped electron beam writing apparatus. Thevariable-shaped electron beam (VSB) pattern writing apparatus operatesas follows: As shown in the figure, the pattern writing apparatusincludes two aperture plates. A first or “upper” aperture plate 410 hasan opening or “hole” 411 in the shape of a rectangle for shaping anelectron beam 330. This shape of the rectangular opening may also be asquare, a rhombus, a rhomboid, etc. A second or “lower” aperture plate420 has a variable-shaped opening 421 for shaping the electron beam 330having passed through the opening 411 of the first aperture plate 410into a desired rectangle. The electron beam 330 that left a chargedparticle source 430 and has passed through the opening 411 is deflectedby a deflector. Then, the electron beam 330 passes through a part of thevariable-shaped opening 421 of the second aperture plate 420, andirradiates a target workpiece 340 mounted on a stage that iscontinuously moving in a predetermined direction (e.g. X-axisdirection). In other words, a rectangular shape capable of passingthrough both of the opening 411 and the variable-shaped opening 421 iswritten in a pattern writing region of the target workpiece 340 mountedon the stage. This method of writing or “forming” a given variable shapeby letting beams pass through both of the opening 411 and the speciallyshaped opening 421 is called a variable shaped beam (VSB) system.

In the electron beam writing mentioned above, highly precise uniformityof the line width is required in the surface of a target workpiece, suchas a mask surface, when writing a pattern on the target workpiece.However, in the electron beam writing, a phenomenon called a proximityeffect occurs when electron beams irradiate a circuit pattern on a maskwhere resist is applied. The proximity effect is generated by thebackward scattering of electron beams penetrating a resist film,reaching a layer thereunder to be reflected, and being incident into theresist film again. As a result, a dimension change deviated from adesired dimension occurs when a pattern is written. On the other hand,after writing a pattern, when developing the resist film or etching thelayer thereunder, a dimension change called a loading effect caused bydensity difference of a circuit pattern occurs.

As the loading effect being a dimension change occurring in a chargedparticle beam writing represented by an electron beam writing, thefollowing can be cited as examples: a loading effect generated whendeveloping a resist film, a loading effect generated when etchingchromium (Cr) serving as a shading film under a resist film, and aloading effect generated when a pattern dimension change is produced bychemical mechanical polishing (CMP). In the electron beam writing, morehighly precise uniformity of the line width in a mask surface isrequired with narrowing the line width of a pattern. Therefore, aloading effect correction to correct the dimension change caused by theloading effect is needed. The correction is executed, based on a designline width of a circuit pattern (design pattern), by performing writingusing a dimension resized by previously estimating a dimension changeamount (dimension error) caused by a loading effect, and then a desireddesign line width can be obtained after the loading effect produced byetching etc. For example, when a calculated dimension change amountproduced by a loading effect becomes positive (direction of the linewidth becoming wide), the circuit pattern is irradiated after beingresized so that the line width may become narrower than the design linewidth by the dimension change amount produced by the loading effect.

As to the loading effect correction, it is disclosed that a pattern datacorrection amount is calculated by adding a loading effect correctionamount for correcting a dimension change produced in etching, to aprocess resizing amount for correcting a pattern shape error generatedin writing and developing. ((Refer to, e.g., Japanese Unexamined PatentPublication No. 2004-279950 (JP-A-2004-279950))

As the method of resizing a pattern for correcting the loading effect,there are a method of performing correction by changing a dose amount ofelectron beams after the shot division and a method of correcting thepattern shape itself before the shot division. The latter method will bedescribed hereinafter.

Conventionally, when correcting a pattern shape itself, namely resizinga pattern dimension, a uniform resizing amount has been used for apattern included in a certain small region regardless of the patternshape. However, with an increase in miniaturization of a writingpattern, problems have occurred because of using a uniform correctionamount (resizing amount) for all of a pattern. For example, in the caseof a resizing amount being 20 nm, if a figure pattern with a width of 1μm is resized to be narrower, the width becomes 980 nm and its reductionrate is 2%. On the other hand, if a figure pattern with a width of 100nm is resized to be narrower, the width becomes 80 nm and its reductionrate is 20%. That is, an over-correction is made for the figure patternwith a width of 100 nm. Thus, when using a uniform resizing amount in asmall region, the writing cannot be highly precisely executed because anover-corrected pattern is formed.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a highly precisemethod of resizing a pattern, with respect to a dimension change causedby a loading effect, and to provide an apparatus that writes a patternusing pattern data resized by the method.

In accordance with one aspect of the present invention, a method forresizing a pattern to be written by using lithography technique includescalculating a first dimension correction amount of a pattern forcorrecting a dimension error caused by a loading effect, for each smallregion made by virtually dividing a writing region of a target workpieceinto meshes of a predetermined size, based on an area density of theeach small region, calculating a second dimension correction amount inaccordance with a line width dimension of the pattern to be written inthe each small region, correcting the first dimension correction amountby using the second dimension correction amount, and resizing the linewidth dimension of the pattern by using a corrected first dimensioncorrection amount, and outputting a result of the resizing.

In accordance with another aspect of the present invention, a method forresizing a pattern to be written by using lithography technique includescalculating a first dimension correction amount of a pattern forcorrecting a dimension error caused by a loading effect, for each smallregion made by virtually dividing a writing region of a target workpieceinto meshes of a predetermined size, based on an area density of theeach small region, calculating a second dimension correction amount inaccordance with an adjacent pattern to be written around the pattern tobe written in the each small region, correcting the first dimensioncorrection amount by using the second dimension correction amount, andresizing a line width dimension of the pattern by using a correctedfirst dimension correction amount, and outputting a result of theresizing.

In accordance with another aspect of the present invention, a method forresizing a pattern to be written by using lithography technique includescalculating a first dimension correction amount of a pattern forcorrecting a dimension error caused by a loading effect, for each smallregion made by virtually dividing a writing region of a target workpieceinto meshes of a predetermined size, based on an area density of theeach small region, calculating a second dimension correction amount inaccordance with a line width dimension of the pattern to be written inthe each small region, calculating a third dimension correction amountin accordance with an adjacent pattern to be written around the patternto be written in the each small region, correcting the first dimensioncorrection amount by using the second and the third dimension correctionamounts, and resizing the line width dimension of the pattern by using acorrected first dimension correction amount, and outputting a result ofthe resizing.

In accordance with another aspect of the present invention, a chargedparticle beam writing method includes inputting line width dimensiondata of a pattern, which has been resized by using a dimensioncorrection amount calculated by correcting a basic correction amount ofthe pattern calculated for correcting a dimension error caused by aloading effect for each small region made by virtually dividing awriting region of a target workpiece into meshes of a predeterminedsize, based on an area density of the each small region, in accordancewith a line width dimension of the pattern to be written in the eachsmall region, and writing the pattern in a predetermined region of thetarget workpiece using a charged particle beam, based on inputted linewidth dimension data of the pattern.

In accordance with another aspect of the present invention, a chargedparticle beam writing method includes inputting line width dimensiondata of a pattern, which has been resized by using a dimensioncorrection amount calculated by correcting a basic correction amount ofthe pattern calculated for correcting a dimension error caused by aloading effect for each small region made by virtually dividing awriting region of a target workpiece into meshes of a predeterminedsize, based on an area density of the each small region, in accordancewith an adjacent pattern to be written around the pattern to be writtenin the each small region, and writing the pattern in a predeterminedregion of the target workpiece using a charged particle beam, based oninputted line width dimension data of the pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 1;

FIG. 2 shows an example of a pattern described in Embodiment 1;

FIG. 3 shows an example of a relation between a resizing amount and aline width described in Embodiment 1;

FIG. 4 shows an example of before and after resizing the figure patternof FIG. 2;

FIG. 5 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 2;

FIG. 6 shows an example of a pattern described in Embodiment 2;

FIG. 7 shows an example of the distribution described in Embodiment 2;

FIG. 8 shows an example of a sample pattern for checking the influenceof distance between the pattern concerned and the adjacent patterndescribed in Embodiment 2;

FIG. 9 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 3;

FIG. 10 shows an example of a writing pattern described in Embodiment 3;

FIG. 11 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 4;

FIG. 12 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 4;

FIG. 13 is a schematic diagram showing an example of the structure of apattern writing apparatus; and

FIG. 14 shows a schematic diagram describing operations of aconventional variable-shaped electron beam writing apparatus.

DETAILED DESCRIPTION OF THE INVENTION Embodiment 1

FIG. 1 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 1. In the figure, a series of steps as theresizing method of a writing pattern are executed as follows: a step ofcalculating a loading effect correction amount l₀ (S102), a step ofcalculating a dimension correction amount Δl₁ in accordance with apattern shape (S104), a step of correcting the loading effect correctionamount by using the dimension correction amount (S106), and a step ofresizing (S108).

In S102, as a calculation step of a loading effect correction amount (anexample of a first calculation step), a loading effect correction amountl₀ (first dimension correction amount) of each small region iscalculated. First, a writing region of a mask substrate being a targetworkpiece is virtually divided into meshes of a predetermined size. Itis preferable to set the size to be approximately equal to or less than1/10 of the influence range of the loading effect. For example, the sizeof about 0.5 mm to 1 mm is suitable as a mesh size.

FIG. 2 shows an example of a writing pattern described in Embodiment 1.For example, a figure pattern 10 shown in FIG. 2 as an example iswritten in one of a plurality of small regions (meshes) made byvirtually dividing the writing region of a mask substrate used as atarget workpiece into meshes of a predetermined size. As shown in thefigure, the figure pattern 10 to be written has a line width of V₁-V₃ inthe lengthwise direction and W₁-W₃ in the lateral direction.

Next, when the coordinates of each small region are defined as (i, j),an area density ρ(i, j) of a pattern to be written, included in eachsmall region is calculated. Then, by using the calculated area densityρ(i, j) of the pattern and an influence coefficient F(i, j) of othersmall region affecting the small region currently concerned, the loadingeffect correction amount l₀ (basic correction amount or the firstdimension correction amount) can be calculated by the following formula(1):

λ₀ =ΣF(i, j)·ρ(i, j)   (1)

However, as mentioned above, since the loading effect correction amountl₀ calculated above is a uniform value in the small region (mesh)concerned, an over-correction may be made depending upon the line widthdimension of the pattern. Therefore, a correction as described belowwill be executed.

In S104, as a calculation step of a dimension correction amount Δl₁ inaccordance with a pattern shape (an example of a second calculationstep), a dimension correction amount Δl₁ (second dimension correctionamount) in accordance with a line width dimension of a pattern to bewritten in a small region is calculated.

FIG. 3 shows an example of a relation between a resizing amount and aline width described in Embodiment 1. As shown in the figure, as aresult of measurement by an experiment, it is found by the inventorsthat in the case of a line width being narrower (smaller) than around acertain line width V₀, a suitable dimension correction amount L forresizing is smaller than the calculated loading effect correction amountl₀. Similarly, in the case of a line width being narrower than around acertain line width W₀ which is equal to the line width V₀, a suitabledimension correction amount L for resizing is smaller than thecalculated loading effect correction amount l₀. This relation can beapproximated by a linear function and shown as an approximation line inFIG. 3. In Embodiment 1, according to this relation, the dimensioncorrection amount L for resizing is made to be the most appropriate bycorrecting the loading effect correction amount l₀ by using a calculateddimension correction amount Δl₁ in accordance with a pattern shape. Thatis, when a required line width V is narrower (namely, its dimensionalvalue is smaller) than the line width V₀, or a required line width W isnarrower (namely, its dimensional value is smaller) than the line widthdimension W₀, the dimension correction amount Δl₁ is calculated for eachdimension, based on the relation shown in FIG. 3.

In S106, as a correction step, the loading effect correction amount l₀is corrected by using the dimension correction amount Δl₁ calculated inthe step mentioned above. Thus, a suitable dimension correction amount L(resizing amount) can be obtained. It is possible to calculate andobtain the dimension correction amount L by the formula (2) shown below.

L=λ ₀−Δλ₁   (2)

The loading effect correction amount l_(o) is corrected by using thedimension correction amount Δl₁ herein as shown in the formula (2), butit is not restricted thereto. The loading effect correction amount l₀may be calculated as the dimension correction amount L, based on therelation shown in FIG. 3.

In S108, as a resizing step, the line width dimension of the figurepattern 10 is resized by using the loading effect correction amount l₀that has been corrected by the dimension correction amount Δl₁, and thenthe resized result is output.

FIG. 4 shows an example of before and after resizing the figure patternof FIG. 2. In FIG. 4, the figure pattern 10 of before resizing and afigure pattern 12 of after resizing are shown. For example, when theline width V₁ and the line width W₃ of the figure pattern 10 shown inFIG. 2 are narrower than the line width V₀ (or line width W₀) that isused as a threshold value, the resizing amount becomes as shown in FIG.4. With respect to the line width V₁, the resizing amount becomes aresizing amount L₃ which is smaller than the resizing amount L₁ thatcorresponds with the loading effect correction amount l₀. Besides, withrespect to the line width dimension W₃, the resizing amount becomes aresizing amount L₂ which is smaller than the resizing amount L₁ thatcorresponds with the loading effect correction amount l₀. With referenceto FIG. 2, the top lateral side is one side of the pattern whose linewidth is V₁, one side of the pattern whose line width is V₂, and oneside of the pattern whose line width is V₃. That is, one side of thepattern whose width is the line width V₁ is shared as one side of thepattern whose width is the line width V₂ and one side of the patternwhose width is the line width is V₃. In this case, it is desirable touse the resizing amount L₃ in order not to produce an over-correctionfor the side shared. Thus, in the case of the pattern having a sideshared by the line width dimension larger than or equal to the linewidth V₀ (or the line width W₀) used as a threshold value and by theline width dimension smaller than the line width V₀ (or the line widthW₀), with respect to the side shared, the dimension correction amountΔl₁ is used even for the dimension of the line width larger than orequal to the line width V₀ (or line width W₀). As to other line widthslarger than or equal to the line width V₀ (or line width W₀) serving asa threshold value, it is both executable to calculate the dimensioncorrection amount Δl₁ or not to calculate it. Even if the calculation isexecuted, no difference is generated because the calculated valuebecomes 0 (zero). From a viewpoint of shortening the calculation time,it is preferable to perform calculation only for a line width narrowerthan the line width V₀ (or line width W₀) used as a threshold value.

As mentioned above, by correcting the loading effect correction amountl₀ to be in accordance with the shape of a pattern, especially a linewidth, the over-correction can be controlled and a more suitabledimension correction amount L (resizing amount) can be calculated.

Embodiment 2

In Embodiment 1, the resizing amount is corrected according to the shapeof the pattern concerned. In Embodiment 2, the resizing amount iscorrected according to the influence from a figure pattern located inthe vicinity.

FIG. 5 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 2. In the figure, a series of steps as theresizing method of a pattern are executed as follows: a step ofcalculating a loading effect correction amount l₀ (S102), a step ofcalculating a dimension correction amount Δl₂ in accordance with thedistance from an adjacent pattern and the shape of the adjacent pattern(S204), a step of correcting the loading effect correction amount byusing the dimension correction amount (S206), and a step of resizing(S208).

Since the calculation step of the loading effect correction amount(S102) is the same as that of Embodiment 1, description thereof isomitted herein.

FIG. 6 shows an example of a pattern described in Embodiment 2. Forexample, in the case of calculating the resizing amount of a figurepattern 20 shown in FIG. 6, the figure pattern 20 is affected, as theloading effect, by an adjacent figure pattern 30 located in thevicinity. Therefore, the influence of the adjacent figure pattern 30upon the loading effect correction amount l₀ needs to be correctedaccording to Embodiment 2.

In S204, as a step of calculating a dimension correction amount Δl₂ inaccordance with the distance from an adjacent pattern and the shape ofthe adjacent pattern (an example of the second or the third calculationstep), the dimension correction amount Δl₂ (the second or the thirddimension correction amount) is calculated in accordance with anadjacent pattern to be written around the pattern concerned which is tobe written in a small region.

Moreover, the inside of the small region (inside of the mesh) is furtherdivided into further smaller meshes. FIG. 7 shows an example of aGaussian distribution described in Embodiment 2. It can be consideredthat the influence from other region upon the unit region coordinates(x₀, y₀) being a part of the required figure pattern 20 is in accordancewith the Gaussian distribution as shown in FIG. 7 as an example. TheGaussian function G (x, y, x₀, y₀) can be expressed by the formula (3)shown below.

$\begin{matrix}{{G\left( {x,y,x_{0},y_{0}} \right)} = {A\; ^{\frac{{({x - x_{0}})}^{2} + {({y - y_{0}})}^{2}}{2\delta^{2}}}}} & (3)\end{matrix}$

The coefficient A can be obtained by an experiment. The dimensioncorrection amount Δl₂ being the influence from the adjacent figurepattern 30 upon the region coordinates (x₀, y₀) which is a part of thefigure pattern 20 can be calculated by the formula (4) shown below usingthe Gaussian function G (x, y, x₀, y₀).

Δλ₂(x ₀ ,y ₀)=∫G(x,y,x ₀,y₀)·ƒ(x,y)dxdy   (4)

The probability function F (x, y) is expressed by the following formula(5):

$\begin{matrix}{{f\left( {x,y} \right)} = \left\{ \begin{matrix}1 & ({pattern}) \\0 & \left( {{no}\mspace{14mu} {pattern}} \right)\end{matrix} \right.} & (5)\end{matrix}$

As no influence is given from the position of “no pattern”, what isnecessary is just to make the value of that position be 0 (zero). Thus,the dimension correction amount Δl₂ can be calculated by performing anintegration for each second small region made by virtually dividing thesmall region into further smaller meshes.

FIG. 8 shows an example of a sample pattern for checking the influenceof the distance between the pattern concerned and the adjacent patterndescribed in Embodiment 2. For example, with keeping different distancesS₁ to S₃, some pairs of reference patterns 40 each having a certain unitarea as shown in FIG. 8 are arranged in a large region, such as a 100 μmsquare, where the influence of the loading effect can be disregarded. InFIG. 8, there are provided groups: a group of a reference pattern 40 aand a reference pattern 40 b whose distance is S₁, a group of areference pattern 40 c and a reference pattern 40 d whose distance isS₂, and a group of a reference pattern 40 e and a reference pattern 40 fwhose distance is S₃. The distance between the groups is remote enoughto disregard the influence of the loading effect. By writing such asample pattern and measuring the line width after etching the pattern,the coefficient A of the Gaussian function G mentioned above may bedefined.

The formula (4) can also be used to calculate with respect to all theregion inside the figure pattern 20. However, since the resizing targetis the perimeter sides of the pattern, it is preferable not to calculatewith respect to the divided mesh at the center of the figure pattern 20from the viewpoint of shortening the calculation time.

In S206, as a correction step, the loading effect correction amount l₀is corrected by using the dimension correction amount Δl₂ calculated inthe step mentioned above. Therefore, a suitable dimension correctionamount (resizing amount) L can be obtained. It is possible to calculateand obtain the dimension correction amount L by the formula (6) shownbelow.

L=λ ₀+Δλ₂   (6)

In S208, as a resizing step, the line width dimension of the figurepattern 20 is resized by using the loading effect correction amount l₀that has been corrected by the dimension correction amount Δl₂, and thenthe resized result is output.

As mentioned above, it is possible to obtain the suitable dimensioncorrection amount (resizing amount) L by adding the dimension correctionamount Δl₂ to the loading effect correction amount l₀.

Embodiment 3

In Embodiment 2, calculation is performed for each unit region dxdy andeach result of the calculation is added, as integrated calculation. InEmbodiment 3, there will be explained a method of correcting theinfluenced of the adjacent pattern by a simpler way though the precisionmay be decreased.

FIG. 9 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 3. In the figure, a series of steps as theresizing method of a pattern are executed as follows: a step ofcalculating a loading effect correction amount l₀ (S102), a step ofcalculating a dimension correction amount Δl₂′ in accordance with thedistance between gravity centers of the pattern concerned and anadjacent pattern and the area of the adjacent pattern (S304), a step ofcorrecting the loading effect correction amount by using the dimensioncorrection amount (S306), and a step of resizing (S308).

Since the calculation step of the loading effect correction amount(S102) is the same as that of Embodiment 1, description thereof isomitted herein.

FIG. 10 shows an example of a writing pattern described in Embodiment 3.In the figure, there shown are the figure pattern 20 and the adjacentfigure pattern 30 which are the same as those in FIG. 6. According toEmbodiment 3, disregarding the shape of the adjacent figure pattern 30,the influence of the adjacent figure pattern 30 upon the loading effectcorrection amount l₀ is corrected by using a distance S between thegravity centers of the gravity center G1 of the figure pattern 20 andthe gravity center G2 of the adjacent figure pattern 30, and the area Bof the adjacent figure pattern 30.

In S304, as a step of calculating a dimension correction amount Δl₂′ inaccordance with the distance between the gravity centers of the patternconcerned and an adjacent pattern and the area of the adjacent pattern(an example of the second or the third calculation step), the dimensioncorrection amount Δl₂′ (the second or the third dimension correctionamount) is calculated in accordance with an adjacent pattern to bewritten around the pattern concerned which is to be written in a smallregion. Then, the dimension correction amount Δl₂′ being the influencefrom the adjacent figure pattern 30 upon the figure pattern 20 can becalculated by the formula (7) shown below which is a simplified one ofthe formula (4) described in Embodiment 2.

$\quad\begin{matrix}\begin{matrix}{{\Delta\lambda}_{2}^{\prime} = {B \cdot A^{\prime} \cdot ^{\frac{S^{2}}{2\delta^{2}}}}} \\{= {{B \cdot A^{\prime}}{h(S)}}}\end{matrix} & (7)\end{matrix}$

The coefficient A′h(S) maybe obtained by an experiment in advance. Thus,as mentioned above, it is also preferable to simply calculate thedimension correction amount Δl₂′ by using the distance S between thegravity centers of the gravity center G1 of the figure pattern 20 andthe gravity center G2 of the adjacent figure pattern 30, and the area Bof the adjacent figure pattern 30.

In S306, as a correction step, the loading effect correction amount l₀is corrected by using the dimension correction amount Δl₂′ calculated inthe step mentioned above. Therefore, a suitable dimension correctionamount (the resizing amount) L can be obtained. It is possible tocalculate and obtain the dimension correction amount L by the formula(8) shown below.

L=λ ₀+Δλ₂′  (8)

In S308, as a resizing step, the line width dimension of the figurepattern 20 is resized by using the loading effect correction amount l₀that has been corrected by the dimension correction amount Δl₂′, andthen the resized result is output.

As mentioned above, the suitable dimension correction amount (resizingamount) L can be calculated by adding the dimension correction amountΔl₂′ to the loading effect correction amount l₀.

Embodiment 4

FIG. 11 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 4. In the figure, a series of steps as theresizing method of a pattern are executed as follows: a step ofcalculating a loading effect correction amount l₀ (S102), a step ofcalculating a dimension correction amount Δl₁ in accordance with apattern shape (S104), a step of calculating a dimension correctionamount Δl₂ in accordance with the distance from an adjacent pattern andthe shape of the adjacent pattern (S204), a step of correcting theloading effect correction amount by using the dimension correctionamount (S406), and a step of resizing (S408).

Since the calculation step of the loading effect correction amount(S102) and the calculation step of the dimension correction amount Δl₁in accordance with a pattern shape (S104) are the same as those ofEmbodiment 1, description thereof is omitted herein. In addition, sincethe calculation step of the dimension correction amount Δl₂ inaccordance with the distance from an adjacent pattern and the shape ofthe adjacent pattern (S204) is the same as that of Embodiment 2,description thereof is omitted. According to Embodiment 4, a more highlyprecise resizing amount L can be obtained by combining Embodiment 1 andEmbodiment 2.

In S406, as a correction step, the loading effect correction amount l₀is corrected by using the dimension correction amount Δl₁ and thedimension correction amount Δl₂ that are calculated in the stepmentioned above. Therefore, when compared with Embodiment 1 orEmbodiment 2, a more suitable dimension correction amount (resizingamount) L can be obtained by the formula (9) shown below.

L=λ ₀−Δλ₁+Δλ₂   (9)

In S408, as a resizing step, the line width dimension of the figurepattern is resized by using the loading effect correction amount l₀ thathas been corrected by the dimension correction amount Δl₁ and thedimension correction amount Δl₂, and then the resized result is output.

As mentioned above, it is possible to obtain a suitable dimensioncorrection amount (resizing amount) L by subtracting the dimensioncorrection amount Δl₁ from the loading effect correction amount l₀ andadding the dimension correction amount Δl₂ to the difference.

Embodiment 5

FIG. 12 is a flowchart showing main steps of a pattern resizing methoddescribed in Embodiment 4. In the figure, a series of steps as theresizing method of a pattern are executed as follows: a step ofcalculating a loading effect correction amount l₀ (S102), a step ofcalculating a dimension correction amount Δl₁ in accordance with apattern shape (S104), a step of calculating a dimension correctionamount Δl₂′ in accordance with the distance between gravity centers ofthe pattern concerned and an adjacent pattern and the area of theadjacent pattern (S304), a step of correcting the loading effectcorrection amount by using the dimension correction amount (S506), and astep of resizing (S508).

Since the calculation step of the loading effect correction amount(S102) and the calculation step of the dimension correction amount Δl₁in accordance with a pattern shape (S104) are the same as those ofEmbodiment 1, description thereof is omitted herein. In addition, sincethe calculation step the dimension correction amount Δl₂′ in accordancewith the distance between gravity centers of the pattern concerned andan adjacent pattern and the area of the adjacent pattern (S304) is thesame as that of Embodiment 3, description thereof is omitted. Accordingto Embodiment 5, a more highly precise resizing amount L can be obtainedby combining Embodiment 1 and Embodiment 3.

In S506, as a correction step, the loading effect correction amount l₀is corrected by using the dimension correction amount Δl₁ and thedimension correction amount Δl₂ that are calculated in the stepmentioned above. Therefore, when compared with Embodiment 1 orEmbodiment 3, a more suitable dimension correction amount (resizingamount) L can be obtained by the formula (10) shown below.

L=λ ₀−Δλ₁+Δλ₂′  (10)

In S508, as a resizing step, the line width dimension of the figurepattern is resized by using the loading effect correction amount l₀ thathas been corrected by the dimension correction amount Δl₁ and thedimension correction amount Δl₂′, and then the resized result is output.

As mentioned above, it is possible to obtain the suitable dimensioncorrection amount (resizing amount) L by subtracting the dimensioncorrection amount Δl₁ from the loading effect correction amount l₀ andadding the dimension correction amount Δl₂′ to the difference.

By performing as described above, the precision of the loading effectcorrection can be further enhanced. Inputting the pattern data resizedby one of the methods of Embodiments mentioned above into a patternwriting apparatus, it becomes possible to write a highly precisepattern.

FIG. 13 is a schematic diagram showing an example of the structure of apattern writing apparatus. In the figure, a pattern writing apparatus100 includes a pattern writing part 150 and a control part 160. Thepattern writing apparatus 100 serving as an example of a chargedparticle beam pattern writing apparatus writes a figure pattern on atarget workpiece 101 using an electron beam being an example of acharged particle beam. The target workpiece 101 includes a mask to beused for manufacturing semiconductor devices. The control part 160includes a control circuit 110 and a writing data processing circuit120. The pattern writing part 150 includes an electron lens barrel 102and a writing chamber 103. The electron lens barrel 102 includes anelectron gun assembly 201, an illumination lens 202, a first apertureplate 203, a projection lens 204, a deflector 205, a second apertureplate 206, an objective lens 207, and a deflector 208. In the writingchamber 103, an XY stage 105 is arranged. On the XY stage 105, thetarget workpiece 101 to be written is laid or “placed”.

Only the structure elements necessary for explaining the writing usingresized pattern data are shown in FIG. 13. It should be understood thatother structure elements may also be included in the pattern writingapparatus 100.

Moreover, in a resizing data generation apparatus 300, resized patterndata mentioned above in each Embodiment is generated and output to thewriting data processing circuit 120. The writing data processing circuit120 converts the inputted pattern data into internal data of theapparatus. Based on the internal data of the apparatus, the patternwriting part 150 is controlled by the control circuit 110 and a desiredfigure pattern is written on the target workpiece.

An electron beam 200 emitted from the electron gun assembly 201irradiates the whole of the first aperture plate 203 having arectangular opening by the illumination lens 202, for example. Thisshape of the rectangular opening may also be a square, a rhombus, arhomboid, etc. At this point, the electron beam 200 is shaped to be arectangle. Then, after having passed through the first aperture plate203, the electron beam 200 of a first aperture image is guided by theprojection lens 204 to reach the second aperture plate 206. The positionof the first aperture image on the second aperture plate 206 iscontrolled by the deflector 205, and thereby the shape and size of thebeam can be changed. After having passed through the second apertureplate 206, the electron beam 200 of a second aperture image isfocus-adjusted by the objective lens 207 and deflected by the deflector208, to reach a desired position on the target workpiece 101 placed onthe XY stage 105 which is movably arranged.

As mentioned above, it becomes possible to write a more highly precisepattern on a target workpiece by using pattern data which has beenresized by performing resizing more highly accurately for a dimensionchange produced by the loading effect.

The embodiments have been described with reference to the concreteexamples. However, the present invention is not limited thereto. Forexample, although the Gaussian function is used in Embodiments 2 and 3,it is also preferable to use other function obtained by performingfitting (approximation) of an experimental result. For example, a doubleGaussian function as shown in the following formula (11) can also beapplied.

$\begin{matrix}{{G\left( {x,y,x_{0},y_{0}} \right)} = {{A\; ^{\frac{{({x - x_{0}})}^{2} + {({y - y_{0}})}^{2}}{2\delta_{0}^{2}}}} + {B\; ^{\frac{{({x - x_{0}})}^{2} + {({y - y_{0}})}^{2}}{2\delta_{1}^{2}}}}}} & (11)\end{matrix}$

In this case, the influence ranges δ₀ and δ₁ may be obtained by anexperiment. This is effective especially when it is difficult to performa perfect approximation by using only one Gaussian function. Moreover,although the primary function is used in Embodiment 1, it is alsopreferable to use other function obtained by performing fitting(approximation) of an experimental result.

While the units which are not directly necessary for explaining thepresent invention, such as the structure of the apparatus and thecontrol methods, are not described, it is possible to suitably selectand use some or all of them when needed. For example, though thedescription of the structure of the control unit for controlling thepattern writing apparatus 100 is omitted, it should be understood thatrequired structures of the control unit can be appropriately selectedand used.

In addition, any pattern resizing method, charged particle beam writingmethod, and charged particle beam writing apparatus that includeelements of the present invention and that can be appropriately modifiedby those skilled in the art are included within the sprit and scope ofthe present invention.

Additional advantages and modification will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A method for resizing a pattern to be written by using lithographytechnique comprising: calculating a first dimension correction amount ofa pattern for correcting a dimension error caused by a loading effect,for each small region made by virtually dividing a writing region of atarget workpiece into meshes of a predetermined size, based on an areadensity of the each small region; calculating a second dimensioncorrection amount in accordance with a line width dimension of thepattern to be written in the each small region; correcting the firstdimension correction amount by using the second dimension correctionamount; and resizing the line width dimension of the pattern by using acorrected first dimension correction amount, and outputting a result ofthe resizing.
 2. The method according to claim 1, wherein the seconddimension correction amount is calculated when the line width dimensionof the pattern is smaller than a predetermined value.
 3. The methodaccording to claim 2, wherein the second dimension correction amount isapproximated by a linear function.
 4. The method according to claim 2,wherein when the pattern has a side shared as one side of the patternwhose line width dimension is larger than or equal to the predeterminedvalue and as one side of the pattern whose line width dimension issmaller than the predetermined value, the side shared is corrected byusing the second dimension correction amount.
 5. A method for resizing apattern to be written by using lithography technique comprising:calculating a first dimension correction amount of a pattern forcorrecting a dimension error caused by a loading effect, for each smallregion made by virtually dividing a writing region of a target workpieceinto meshes of a predetermined size, based on an area density of theeach small region; calculating a second dimension correction amount inaccordance with an adjacent pattern to be written around the pattern tobe written in the each small region; correcting the first dimensioncorrection amount by using the second dimension correction amount; andresizing a line width dimension of the pattern by using a correctedfirst dimension correction amount, and outputting a result of theresizing.
 6. The method according to claim 5, wherein the seconddimension correction amount is calculated by performing an integrationcalculation for each second small region made by further virtuallydividing the small region into meshes.
 7. The method according to claim5, wherein the second dimension correction amount is calculated by usingan area of the adjacent pattern and a distance between gravity centersof the pattern to be written and the adjacent pattern.
 8. A method forresizing a pattern to be written by using lithography techniquecomprising: calculating a first dimension correction amount of a patternfor correcting a dimension error caused by a loading effect, for eachsmall region made by virtually dividing a writing region of a targetworkpiece into meshes of a predetermined size, based on an area densityof the each small region; calculating a second dimension correctionamount in accordance with a line width dimension of the pattern to bewritten in the each small region; calculating a third dimensioncorrection amount in accordance with an adjacent pattern to be writtenaround the pattern to be written in the each small region; correctingthe first dimension correction amount by using the second and the thirddimension correction amounts; and resizing the line width dimension ofthe pattern by using a corrected first dimension correction amount, andoutputting a result of the resizing.
 9. A charged particle beam writingmethod comprising: inputting line width dimension data of a pattern,which has been resized by using a dimension correction amount calculatedby correcting a basic correction amount of the pattern calculated forcorrecting a dimension error caused by a loading effect for each smallregion made by virtually dividing a writing region of a target workpieceinto meshes of a predetermined size, based on an area density of theeach small region, in accordance with a line width dimension of thepattern to be written in the each small region; and writing the patternin a predetermined region of the target workpiece using a chargedparticle beam, based on inputted line width dimension data of thepattern.
 10. A charged particle beam writing method comprising:inputting line width dimension data of a pattern, which has been resizedby using a dimension correction amount calculated by correcting a basiccorrection amount of the pattern calculated for correcting a dimensionerror caused by a loading effect for each small region made by virtuallydividing a writing region of a target workpiece into meshes of apredetermined size, based on an area density of the each small region,in accordance with an adjacent pattern to be written around the patternto be written in the each small region; and writing the pattern in apredetermined region of the target workpiece using a charged particlebeam, based on inputted line width dimension data of the pattern.